Kinetic and mechanistic investigation of the sequential hydrogenation of phenylacetylene catalyzed by OsHCl(CO)(PR3)2 [PR3 = PMe-tert-Bu2 and P-i-Pr3]

Andriollo, Antida; Esteruelas, Miguel A.; Meyer, U.; Oro, Luis A.; Sánchez‐Delgado, Roberto A.; Sola, Eduardo; Valero, Cristina; Werner, Helmut

doi:10.1021/ja00201a024

Cited by 139 publications

(57 citation statements)

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“…This implies that the NR hydrogenation exhibits a first-order behavior with respect to [Os]. This observation is consistent with the work of Andriollo and coworkers 15 and J. S. Parent and colleagues, 18 who suggested that the active complex is a mononuclear species. This figure also shows that the rate of PIP hydrogenation 19 was higher than that of NR hydrogenation, which required higher loading of the catalyst.…”

Section: Univariate Kinetic Experimentssupporting

confidence: 89%

Hydrogenation of natural rubber in the presence of OsHCL(CO)(O₂)(PCY₃)₂: Kinetics and mechanism

Hinchiranan

Prasassarakich

Rempel

2006

J of Applied Polymer Sci

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ABSTRACT:The homogeneous catalyst precursor, OsHCl-(CO)(O 2 )(PCy 3 ) 2 , was utilized for the hydrogenation of natural rubber to convert the unsaturated structure to a saturated form, providing an alternating ethylene-propylene copolymer. A detailed kinetic investigation was carried out by monitoring the amount of hydrogen consumption during the reaction using a gas-uptake apparatus.1 H NMR spectroscopy was used to determine the final olefin conversion to the hydrogenated product. Kinetic data, collected according to a statistical design framework, defined the influence of catalyst and polymer concentration, hydrogen pressure, and reaction temperature on the catalytic activity. The kinetic results indicated that the hydrogenation rate exhibited a first-shifted to zero-order dependence on hydrogen at lower hydrogen pressure, which then decreased toward an inverse behavior at pressures higher than 41.4 bar. The hydrogenation was also observed to be first-order with respect to catalyst concentration, and an apparent inverse dependence on rubber concentration was observed due to the impurities in the rubber. The hydrogenation rate was dependent on reaction temperature, and the apparent activation energy over the temperature range of 125-145°C was found to be 122.76 kJ/mol. Mechanistic aspects of the hydrogenation of natural rubber in the presence of OsHCl(CO)(O 2 )(PCy 3 ) 2 were proposed on the basis of the observed kinetic results. The addition of some acids and certain nitrogen containing materials showed an effect on the hydrogenation rate. The thermal properties of hydrogenated natural rubber indicated that the thermal stability increased with increasing % hydrogenation of the rubber.

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Section: Univariate Kinetic Experimentssupporting

confidence: 89%

Hydrogenation of natural rubber in the presence of OsHCL(CO)(O₂)(PCY₃)₂: Kinetics and mechanism

Hinchiranan

Prasassarakich

Rempel

2006

J of Applied Polymer Sci

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“…Using MHCI(CO)(PiPr3)2 (11, 12) and RuHCI(CO)(PPh,), (15)as starting materials, the complexes M(E-CH = CHMe)CI(CO)-(PiPr3)2 (13,14) and Ru(E-CH=CHR)CI(CO)(PPh3)2 (16 R = Ph; 17: R = H) are similarly prepared. The reactions of 3, 4, and 12 with HC = CC02Me also lead to the formation of vinyl-metal compounds in which the C02Me group is either bound to the u or the p carbon atom of the vinyl ligand. The X-ray crystal struc-…”

Section: Five-and Six-coordinate Vinyl-ruthenium and -Osmium Complexementioning

confidence: 99%

Fünf‐ und sechsfach koordinierte Vinylruthenium‐ und ‐osmium‐Komplexe durch Alkin‐Insertion in Hydridometall‐Vorstufen

1989

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“…1,11 Some examples of chemo-and stereoselective alkyne semihydrogenation have been reported, but very few studies have addressed the mechanism of the reaction or explained the observed selectivity. 4,12,13 For the development of better catalytic systems it is of vital importance to understand the mechanism, enabling a directed search for new catalysts.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Pd(NHC)-Catalyzed Transfer Hydrogenation of Alkynes

et al. 2010

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The transfer semihydrogenation of alkynes to (Z)-alkenes shows excellent chemo-and stereoselectivity when using a zero-valent palladium(NHC)(maleic anhydride)-complex as pre-catalyst and triethylammonium formate as hydrogen donor. Studies on the kinetics under reaction conditions showed a broken positive order in substrate and first order in catalyst and hydrogen donor. Deuteriumlabeling studies on the hydrogen donor showed that both hydrogens of formic acid display a primary kinetic isotope effect, indicating that proton and hydride transfers are separate rate-determining steps. By monitoring the reaction with NMR we observed the presence of a coordinated formate anion and found that part of the maleic anhydride remains coordinated during the reaction. From these observations we propose a mechanism in which hydrogen transfer from formate anion to zero-valent palladium(NHC)(MA)(alkyne)-complex is followed by migratory insertion of hydride, after which the product alkene is liberated by proton transfer from the triethylammonium cation. The explanation for the 2 high selectivity observed lies in the competition between strongly coordinating solvent and alkyne for a Pd(alkene)-intermediate.

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Kinetic and mechanistic investigation of the sequential hydrogenation of phenylacetylene catalyzed by OsHCl(CO)(PR3)2 [PR3 = PMe-tert-Bu2 and P-i-Pr3]

Cited by 139 publications

References 1 publication

Hydrogenation of natural rubber in the presence of OsHCL(CO)(O₂)(PCY₃)₂: Kinetics and mechanism

Hydrogenation of natural rubber in the presence of OsHCL(CO)(O₂)(PCY₃)₂: Kinetics and mechanism

Fünf‐ und sechsfach koordinierte Vinylruthenium‐ und ‐osmium‐Komplexe durch Alkin‐Insertion in Hydridometall‐Vorstufen

Mechanism of Pd(NHC)-Catalyzed Transfer Hydrogenation of Alkynes

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Kinetic and mechanistic investigation of the sequential hydrogenation of phenylacetylene catalyzed by OsHCl(CO)(PR3)2 [PR3 = PMe-tert-Bu2 and P-i-Pr3]

Cited by 139 publications

References 1 publication

Hydrogenation of natural rubber in the presence of OsHCL(CO)(O2)(PCY3)2: Kinetics and mechanism

Hydrogenation of natural rubber in the presence of OsHCL(CO)(O2)(PCY3)2: Kinetics and mechanism

Fünf‐ und sechsfach koordinierte Vinylruthenium‐ und ‐osmium‐Komplexe durch Alkin‐Insertion in Hydridometall‐Vorstufen

Mechanism of Pd(NHC)-Catalyzed Transfer Hydrogenation of Alkynes

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Product

Resources

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Hydrogenation of natural rubber in the presence of OsHCL(CO)(O₂)(PCY₃)₂: Kinetics and mechanism

Hydrogenation of natural rubber in the presence of OsHCL(CO)(O₂)(PCY₃)₂: Kinetics and mechanism